While the head-to-head data is promising for Mourdock, the internal numbers in the Wenzel poll reveal that the state treasurer has a ways to go in defining himself with just two months left before the primary.

Half of primary voters still aren't able to register an opinion of him, leaving his favorable rating at just 31 percent.

Nonetheless, the race remains fluid with roughly half of voters indicating they are open to changing their mind and Mourdock aides believe it demonstrates that Lugar's $2 million in television ads have failed to stymie his challenger's climb.

This may be the most convincing evidence to date that Lugar's positive and negative messaging isn't cutting through and that his spending advantage is being nullified by a media narrative that is raising questions about his detachment from the state.

The tough numbers drop just as Lugar holds a reception for his increasingly difficult reelection bid at his McLean, Va. home Monday evening.

"Are you kidding? After all this #residencyfail, he's having a funder in his hometown of McLean on Monday???," emailed a jubilant GOP aide opposed to Lugar's reelection.